Filter screen



Nov. 8, 1932. J. E. ANDERSON FILTER SCREEN Filed 0G12. l2, 1931 2 Sheets-Sheet ZIM/wanton www NOV. 8, 1932. J. E, ANDERSQN 1,886,460

FILTER SQREEN Filed Oct. 12. 1931 2 Sheets-Sheet 2 Z2 L9 l2 www@ Patented Nov. 8, 1932 UNITED STATES JAMES EEXVIN ANDERSON, OF NASHVILLE, TENNESSEE FILTER SCREEN Application filed October 12, 1931.

My invention relates to a filter screen of general application for separating gases from solid particles carried thereby but more particularly to such a device attachable to a hot air register or other register or outlet casing of heating and Ventilating plants to lter the air passing therethrough from dust and other solid particles.

A general object of my invention is to provide a device of this class simple and durable in construction, of low cost of manufacture and highly eiiicient in its filtering function.

A more particular object of my invention is to provide a filter screen adjustable in boundary dimensions to accommodate the screen to slightly different sizes of registers or outlet casings of heating and Ventilating systems and to variations often found in such registers or casings of supposedly the same sizes. |The adjustable feature of the filter screen of my invention reduces the number of sizes thereof required to be manufactured and also enables a desirably close fit of the screen in the casingl of the register or the like.

ln one form which my invention may take, an expansible and contractible boundary frame is provided and the body of the device within that boundary frame comprises a wire netting of such form and attachment to the boundary frame as to normally expand that frame, the contraction of the frame being secured by pressure thereon from without, the frame contracting against the resilient outward pressure of the wire netting.

Another particular object of my invention is to provide a filter screen having provision for self-sealing all joints between the device and the frame of the register or other vapor outlet to which it is attached so as to prevent the outward passage of air except through the filtering medium of the screen.

The attainment of the last-mentioned object of my invention avoids the serious defect of more or less escape of unfiltered air to which, so far as I am aware, all filter devices of the general class to which my invention pertains are subject. This defect and Serial No. 568,471.

its cause will more clearly appear from the following considerations.

The air currents of heating and Ventilating systems and the dust and other hue particles carried along in suspension therein take of course paths of least resistance; and Where filter screens or the like are interposed at the outlets of the ducts provided for the passage and delivery of the air to the rooms to be heated or ventilated so substantial a resistance is interposed by such devices to the passage of the air therethrough that there is a pronounced tendency for the substantial escape of air with the entrained dust and other particles around the filtering device through even relatively small cracks between that device and the Walls of the outlet casing or register on which it is mounted. A good example of this situation is afforded by the quite common type of hot air heating system in which the t air chiots terminate in box-like casings set in the floor structure of the rooms to be heated, with vthe hot air pipe entering the bottom of the box and the register forming the -cover of the box flush with the floor of the room. l/Vhere filter screens are used in such a system, it is usual practice to mount the screen on the loor of the box over t-he opening of the hot air pipe. As usual practice, this register' box is constructed of thin sheet iron, usually coated with tin, and its floor is rarely a plane surface even when the box is first installed. Moreover even if the floor of this box originally presented a plane surface, the alternate contractions and expansions to which it is subjected by variations of temperature in use soon develop such variations from a. plane surface as to expose substantial cracks between it and the bottom boundary edges of the filter device mounted on that floor. My observation has been that the cracks develop to such an extent as to cause substantial escape of air, with its entrained dust, soot and the like, therethrough from the hot air pipe in the floor of the register box around the filtering screen and upwardly into the room.

lhile all hot air or other vapor heating systems do not present the particular arrangements referred to in the example above, whatever the precise arrangement of the register cil e? of the principles of the invention and is not and its casing and the attachment of a filter screen to either there is a tendency for cracks to develop between the frame of the screen and the register or its casing along the lines of the mounting of the screen thereon, due among other possible causes to unequal expansions and contractions of the metal parts involved` with 'the resulting possibility of escape of unfiltered air through those cracks. So far as l am aware, none of the filter devices of the prior art makes any provision, as is contemplated by my invention, for sealing such cracks if originally present when the filter is installed or for taking up such cracks as they develop in the use ofthe heating system and its associated filter device.

Y In one form which my invention may take, the above-mentioned provision for sealing cracks between the boundary edges of the filter screen and the part on which it is mounted against escape of unfiltered air comprises a body of resiliently compressible material secured around the boundary edges of the filter screen so as to closely engage the surface on which the filter device is mounted. The material used need not have any air filtering properties but instead may simply form so compact a sealing body, under the pressure of the filter against the part on which it is mounted, as to positively prevent the escape of any air therethrough. Preferably, however, a body of loose but resiliently compressible filtering material is used, so that it need not be so compact as to preventy all leakage of -air therethrough since it has the property of filtering whatever air may leak.

Another particular object of my invention is to provide a filter device in which the filtering body or element may be readily removed and replaced by a new one, thus avoiding the necessity of the purchase by the user of an entirely new device when the original filtering element has reached a condition beyond further eective use. f

In one form which my invention may take, this object is attained by tworeadily assembled and disassembled tray-like reticulated frames mounting and supporting the filtering element between them.

The foregoing'objects, principles and advantages of my invention and other objects, irinciples and advantages thereof will more fully appear from the detailed description of a preferred embodiment of the invention hereinafter presented and illustrated in the accompanying Adrawings forming a. part of this specification. It is to be understood, however, that the embodiment described and illustrated is simply one example illustrative to be taken aslimiting the invention to that precise form, the invention including other embodiments and modifica-tions of the embodiment shown, all within the scope of the appended claims.

In the drawings:

Fig. 1 is a perspective view of a hot air or similar vapor register and its casing, set in the floor of a room, and with parts cut away to show the preferred form of my filter device in position on the floor of the register casing over the hot air pipe;

Fig. 2 is a top perspective view, on a somewhat larger scale, of the aforesaid preferred form of my filter device, with its boundary frame expanded;

Fig. 3 is a top plan view of the aforesaid filter device in its expanded condition corresponding to that shown in Fig. 2;

Fig. 4 is a top plan view of the same device in the contracted condition of its boundary frame;

Fig. 5 isa bottom plan view of the device with its boundary frame in expanded condition;

Fig. 6 is a bottom plan view of the device in the contracted position of its boundary frame;

Fig. 7 is a side velevational view;

Fig. 8 is a transverse sectional view on a greatly enlarged scale along the line 8 8 of Fig. 4; and

Fig. 9 is a similar transverse sectional View along the line 9 9 of Fig. 4. Y

The preferred form of my filter device comprises two reticulated and dished body portions, frames, or screens, preferably consisting of wire netting, as indicated by the numerals 10 and 11 in the various views of the drawings.

These two open-work frames 10 and 11 are mounted upon rectangular boundary frames in each of which the four sides are in separate solid metal strips. The boundary frame for the outer wire netting 10 consists of .the two end strips 12 and the two side strips 13, while the boundary frame for the innermost wire netting 11 consists similarly of the two end strips 14 and the two side strips 15, as shown in the various views. i

The separate strips of each of these boundary frames are preferably of angle shape in cross section, as shown in Figs. 8 and 9, and the downwardly disposed part of each strip, as viewed in those figures, is turned back upon itself to secure the free ends of the wires o f the nettings 10 and 11 in supported position on the strips, as is most vclearly shown in those views.

The foregoing arrangement presents two basket-like bodies of wire netting, each with a rectangular boundary frame consisting of four separate side strips as just described. Thus, one of the basket-like bodies has its central portion 10 of wire netting and its boundary frame consisting of the two angleshaped end strips 12 and the two like shaped side strips 13. This is the top portionv of the filter seen in the perspective view of Fig. 2 and'in the top plan views of Figs. 3 and Cil 4. The other basket-like part of the filter consists of the wire netting 11 and the boundary frame having the two angle-shaped end strips 14 and the two like shaped side strips 15. This is the bottom po-rtion seen only in the bottom plan views of Figs. 5 and 6 and in part in the transverse sectional views of Figs. 8 and 9.

These two basket-like portions or bodies of the device are assembled together in nested relation as indicated in Figs. 8 and 9, and when thus assembled they are releasably secured together by bolts 16 extending through apertures provided in the opposed side strips 13 and 15, nuts 17 on the ends of the bolts co-mpleting the attachment.

The two basket-like portions of the device when thus assembled together are designed to support between them the body of material 18 having the property of retaining dust and other solid particles suspended in the air or other vapor passing through the device. Various bodies of loose or porous material may be used for that purpose but my invention preferably contempla-tes the use of a mass of intermingled steel or the like fine strips or s'havings generally termed metallic wool and that is the material intended to be indicated on the drawings.

The metallic wool is of particular advantage for use as a ltering medium in vapor heating or Ventilating systems because of its long wearing properties as compared for eX- ample with other fibrous material of a nonmetallic nature. The metallic wool will in time, of course, become so clogged with deposited dust, soot, etc., from the air passing through the filter or will be so rust-ed out, as to require replacement or substitution of an entirely new device. Vith my improvements as described above, however, replacement of the worn filter element of metallic wool is so easily accomplished that the installation of a new device is not necessary. All that is required is the separation of the two basketlike portions of the device by the removal of the securing bolts and nuts 16, 17 in the manner already described, when the worn filter element can readily be replaced by a new one and the parts again assembled in their required relation, the simplicity of the construction enabling this replacement to be done by the unskilled householder.

It is to be noted that in the arrangement shown and described the dished forms of the wire nettings 10 and 11 present their boundary frames in the expanded condition shown in Figs. 2, 3 and 5, in which condition the end strips 12 of the one frame and the end strips 14e of the other frame are in a. position outwardly of the ends of the respective side strips 13 and 15 of the two frames, and likewise the respective side strips 13 and 15 are outwardly of the ends of the first-mentioned strips 12 and 14. Itis also to be noted that an inward pressure against the end and side strips of the two frames would move those strips inwardly against the yielding resistance of the wire frames 10 and 11 to the contracted position of the boundary frames shown in Figs. a and 6.

Thus, by their expansibility and contractability, these two boundary fran es of my filter device enable an adiustment in boundary dimensions to accommodate the screen to slightly different sizes of registers or outlet casings and to variations often found in registers or casings of supposedly the same size. This adjustable feature of the filter screen of my invention reduces the number of sizes thereof required to be manufactured and also enables a. desirably close lit of the screen to the casing of the register or the like. For example, when using the screen in a register box, such as shown in Fig. 1, the screen may be contracted to position it in the box and then the expansion of the boundary frame under the resilient outward pressure of the wires will produce a close lit of the screen against the adjacent side walls of the box.

To increase the flexibility of the rim. portion of the dished or basket-like wire nettings 10 and 11, the wires may be severed along the corners 19, if desired. Also the angle and extent of bulge of. the wire nettings 10 and 11 forming the central reticulated body and the angles which the faces of each of the strips or bars of the boundary frame make with respect to each other and with respect to the central reticulated body may be varied as desired or as found most convenient for the mounting of the device.

Due to causes hereinbefore stated, cracks are apt to develop between the lower rim edges of the boundary frame of any filter device and the surface on which it is mounted. Tn addition, in the particular form of filter device of my invention here shown the expansion of the frame causes corner openings which must be sealed aga inst the escape of unfiltered air. Tn the preferred form of mv invention provision is made for sealing all such cracks and openings against the escape of unfiltered' air by extending the metallic wool of the filter member beyond the space between the wire nettings 10 and 11 downwardly between the opposed members of the boundary frames to expose a fringe of the body of metallic wool around the entire lower rim edge of the device so that this fringe comes into close contact with the surface of the register or casing on which it is mounted. The fringe of the metallic wool body thus projecting beyond the lower rim edges of the device is shown in Figs. 2 and 8. wWhen the device is mounted, for example as shown in Fig. 1, the fringe of metallic wool not only fills any openings at the corners of the boundary frame but also provides a cushion between the lower rim edges of the frame and lil) the surface of the register or casing on which it is mounted which cushion follows up any cracks which develop so as to completely fill t ie same and prevent the escape therethrough of any unfiltered' air. rlhus the filtering medium automatically functions also as the sealing body and with the same high efficiency for filtering air, all of which presents the entire device of minimum parts and trouble in use since it is unnecessaryto have a special sealing body.

l/Vhat I claim is:

l. A filter device of the class described comprising a reticulated and dished body portion resiliently compressible along its bound'- ary rim and an eXpansible and contractible frame secured to said body portion along said rim and adapted to mount said filter frame.

2. A lter device of the class described comprising' a .dished body portion of wire netting, a filtering member carried thereby7 and a supporting boundary frame of relatively movable parts to which the'rim of said body portion is secured whereby the bound ary dimensions of said lter device may be adjustably varied by pressing the parts of said frame inwardly of said body portion or pulling them outwardly.

8. A filter device of the class described comprising a dished body portion of wire netting rectangular along its rim, a filtering member carried thereby, and a rectangular supporting frame of relatively movable sides to which the rim of said body portion is secured' whereby the transverse dimensions of said filter device may be adjustably varied by pushing the sides of said frame inwardly or pulling them outwardly of said body portion.

4:. A filter device of the class described comprising a mass of metallic wool as a filter member, an open framework holding said mass in position, said open framework having strip metal boundary edges adapted to mount the filter on a register casing or the like, said metallic wool being held in position in a manner to project a fringe thereof beyond said boundary edges to contact a wall of said casing when the filter device is` mounted thereon.

5. A filter device of the class described comprising two open frames with strip metal boundary edges in opposed assembly and a mass of metallic wool held between said frames and projecting outwardly from between said' opposed strip metal boundary edges in a manner to contact the surface on which said filter device is mounted.

In testimony whereof l hereunto afHX my signature.

JAMES ERW'N ANDERSON. 

